Apparatus for continuous measurement and control of shive content



y 31, 1966 M. A. KEYES 3,253,740

APPARATUS FOR CONTINUOUS MEASUREMENT AND CONTROL OF SHIVE CONTENT FiledDec. 10, 1964 I NVEN TOR.

J/orv'on /i Hqyes TTOR NE YS United States Patent 3 253,740 APPARATUSFOR CONTINUOUS MEASUREMENT AND CONTROL OF SHIVE CONTENT Marion A. Keyes,South Beloit, lll., assignor to Beloit Corporation, Beloit, Wis., acorporation of Wisconsin Filed Dec. 10, 1964, Ser. No. 417,376 9 Claims.(Cl. 222-52) The present invention relates to a continuous device forcontrolling the quantity of uncooked chunks or shives in a papermakingprocess.

The problem of shive control is particularly troublesome in semichemicalpulping processes where it is important to achieve the correct degree ofrefining of the pulp before it is formed into the web. In such systems,it is necessary to operate between the extremes of too little refining,in which case there is a loss of stock forming material, and too muchrefining prior to washing, which adversely affects the drainageproperties of the stock.

The system of the present invention provides a continuously operablesensing and recording mechanism for monitoring the shive concentrationin the stock feed. In accordance with the invention, the stock from aheadbox is supplied under a constant hydrostatic head to a metering tubein which there is an adjustably positionable constriction means in theform of a plug. The constriction means and the internal wall of themetering tube cooperate to define an orifice of size such that thefibrous portion of the stock can pass freely therebetween, but theshives are trapped and eventually build up a deposit in the orifice.Fluid flow sensing means are provided to sense the flow rate of materialpassing through the metering tube, and when an accumulation of theshives causes a diminution of the flow rate of stock through the tube,the flow sensing means operates other devices to first withdraw the plugand thereby enlarge the orifice in the tube, second, to flush the tubewith water while diverting the stock fiow therefrom, and third, to senda signal to a counting device. A timer is provided to control theintroduction of flushing water to a predetermined time interval. At theconclusion of the interval, the apparatus is reset, the plug moved backinto constricting relation within the tube, and the flow of stockthrough the metering tube is resumed. The counter, actuated by theimpulses from the relay or other device which actuates the variousmechanisms associated with the metering tube, is cycled by means ofanother timer device so that it counts the number of actuations of therelay for a predetermined time interval dependent upon the setting ofthe timer. This intelligence is then transferred to arecorder-controller which, in a preferred form of the invention,compares this intelligence with a control. When the number of actuationsof the relay per interval of time exceeds that which has been programmedinto the recorderc-ontroller, the recorder-controller issues a controlsignal which can then be used to modify a process variable in thedirection of reducing the amount of shives retained in the stock.

An object of the present invention is to provide a continuously operableshive monitoring and measuring device for papermaking operations.

Another object of the invention is to provide a continuous system formonitoring shive contents to produce a control signal which can be usedto adjust the shive concentration to desired limits.

Still another object of the invention is to provide a device for thecontinuous monitoring of stock which is completely automatic inoperation.

Other objects and features of the present invention will become apparentto those skilled in the art from the following detailed description ofthe attached sheet of 3,253,740 Patented May 31, 1966 drawings whichillustrates a preferred embodiment of the invention.

In the single figure of the drawings, reference numeral 10 indicatesgenerally a headbox for supplying papermaking stock at a constanthydrostatic pressure. Stock is introduced into the headbox 10 through aninlet line 11, and a pair of weirs 12 and 13 are positioned in spacedrelation within the headbox 10. Stock is continuously removed from theheadbox 10 in the region between the Weirs 12 and 13 by means of anoutlet line 14 while the overflow beyond the weir 13 is returned to theprocess stream by means of a line 16.

The stock in the line 14 is directed to a four-way valve 17 whichselectively introduces the stock or water from a water line 18 into ametering tube generally indicated at reference numeral 19 in thedrawings. The metering tube 19 is generally cylindrical inconfiguration, and contains an outwardly flared bell portion 21 at thedischarge end thereof. Located in the bell-shaped discharge portion 21is a conical plug 22 which is adjustably positionable within thedischarge outlet 21. The plug 22 is mounted on a stem 23 which isreceived within a cylinder 24. A piston 26 is carried by the stem 23 andis operable in response to air pressure injected therein to move theplug 22 up and down, and thereby provide a greater or a lesserconstriction to the flow of material through the metering tube 19.Improved results are obtained if the plug 22 is also rotated, and tothis end, there is provided a pulley 27 driven by a belt 28, and havinga key therein engaging an elongated slot 29 formed in the stem 23. Thebelt 28 thus provides a driving connection to the stem 23, whilepermitting vertical movement of the stem 23 when required.

The stock after passing through the valve 17 actuates a fluid flowsensor 31, such as a flow meter. The stock in normal operation thenpasses into the metering tube 19 and flows between the inner wall of thetube 19 and the plug 22, the two defining a restricted orifice 32 whichis of suflicient size to permit free passage of the fiber containingstock through the bell-shaped discharge outlet 21, while retaininglarger shives therein.

The flow meter 31 is in a line containing a valve 33 and a flowcontroller 34 which is connected to a pneumatically operated relay 36.An air line 37 supplies compressed air for operation of the relay.Closing of the relay 36 operates to energize a solenoid 38 which changesthe position of the four way valve 17 from one in which stock isintroduced into the metering tube 19 to one in which water from the line18 is introduced into the metering tube 19 to flush the accumulatedresidue from within the column. During flushing, the stock is divertedto the process stream by means of a line 39.

Closing of the relay 36 also operates to energize a solenoid 41 whichactuates a three way valve 42. Compressed air is introduced through thevalve 42 from an air line 43. Upon actuation of the solenoid 41, the airin the line 43 is injected into a line 44 which supplies the air underpressure to the cylinder 24 at a point above the piston 26, and causesthe piston to move downwardly, and carry with it the plug 22. Theremoval of the constriction from the throat of the metering tube therebypro vides for more complete flushing of the accumulated materials fromwithin the metering tube during the flushing cycle.

The duration of the flushing cycle is determined by the setting of atimer 46 associated with the relay 36. The timer 46 provides for openingof the four way valve 17 for a predetermined interval of time, so thateach flushing cycle is of exactly the same duration. After the intervalprescribed by the timer 46 has expired, the pneumatic relay 36 isdeenergized, thereby deenergizing the solenoid 38 and the solenoid 41.When this occurs, the flow of stock into the metering tube 19 is resumedthrough the four-way valve 17 and the flow meter 31. The constrictionprovided by the plug 22 is again re-introduced into the discharge end ofthe metering tube 19 by providing air pressure on the opposite-side ofthe piston 26, by means of a line 47 connected to the three-way valve42. A normal operation is then resumed, until such time as the How meter31 again senses a reduction in the fiow through the metering tube 19caused by the accumulation of shives in the orifice 32.

The number of operations of the pneumatic relay 36 per specifiedinterval of time is used as a measure of the shive concentration in thestock. Each time the pneumatic relay 36 operates to commence flushing ofthe metering tube 19, a signal pulse is supplied by means of a line 48from the relay 36 to a counter 49. The counter 49 is cycled by a timer51 to operate over a predetermined time interval. At the conclusion ofsuch time interval, the counter 49 is reset by operation of the timer51, and the accumulated counts which have been fed to the counter 49 aretransmitted by means of a line 52 to a recorder-controller 53. In thelatter, the intelligence inherent in the transmission of the data fromthe counter 52 is compared with a predetermined program, to therebysense automatically whether the amount of shives in the stock has becomeexcessive. To take a specific example, if the timer 51 is set for a15-minute interval, and it has been predetermined that the number offlushings for a l5minute period which would be characteristic of aproperly refined stock is three, and the counter 49 provides fourimpulses during its cycling time, the recordercontroller 53 immediatelyputs out a control signal through a line 54 which modifies a processvariable in the direction of reducing the amount of shives in the stock.This can be accomplished by using the control signal to set the plugposition on a prebrealter refiner, or the reject rate on the stockscreen.

From the foregoing, it will be understood that the device of the presentinvention provides a completley automatic system for monitoring andcontrolling the amount of shives in a papermaking stock. The systemlends itself to complete automation since no operator is required oncethe timers and the recorder-controller have been preset.

It should be understood that various modifications can be made to thedescribed embodiments without departing from the scope of the presentinvention.

I claim as my invention:

1. A continuous shive control device comprising a metering means, meansfor supplying stock to said metering means under a constant hydrostatichead, a constriction means in said metering means providing an orificefor the flow of stock therethrough, sensing means operable to determinea predetermined diminution of flow about said constriction means, andmeans operable in response to operation of said sensing means to countthe number of operations of said sensing means per predetermined timeinterval.

2. A continuous shive control device comprising a metering tube, meansfor supplying stock to said metering tube under a constant hydrostatichead, a constriction means adjustably positionable in said tube toprovide therein a passage of reduced cross-sectional dimensions, flowmetering means sensing the flow through said metering tube, valve meansoperable to terminate flow of stock into said metering tube and tointroduce water therein for flushing accumulated material from saidpassage in response to sensing of a predetermined reduction in flow bysaid flow metering means, and means for counting the number ofoperations of said valve means per predetermined time interval.

3. A continuous shive control device comprising a metering tube, meansfor supplying stock to said metering tube under a constant hydrostatichead, a constriclll iii)

tion means adjustably positionable in said tube to provide therein apassage of reduced cross-sectional dimensions, flow metering meanssensing the fiow through said metering tube, valve means operable toterminate the flow of stock into said metering tube and to introducewater therein for flushing accumulated material from said passage inresponse to the sensing of a predetermined reduction in flow by saidflow metering means, timer means controlling the introduction of waterto a predetermined time interval, and means for counting the number ofoperations of said valve means per predetermined time interval.

4. A continuous shive control device comprising a metering tube, meansfor supplying stock to said metering tube under a constant hydrostatichead, valve means arranged to selectively introduce said stock to saidmetering tube and flushing Water into said metering tube, in adjustablypositionable plug in said tube providing a constriction for the flow ofstock therethrough, flow sensing means positioned to sense the flow ofstock into said tube, relay means operable by said sensing means tooperate said valve means to terminate introduction of stock and injectflushing water into said metering tube, means operable by said relaymeans to simultaneously move said plug into a position where said plugprovides a lesser constriction to the passage of flushing water than itdoes to stock passage, a timer means controlling introduction offlushing water to said tube to a predetermined time interval, andcounting means for counting the number of operations of said relay meansin a predetermined time interval.

5. The device of claim 4 which also includes means for rotating saidplug within said metering tube.

6. A continuous shive control device comprising a metering tube, meansfor supplying stock to said metering tube under a constant hydrostatichead, valve means arranged to selectively introduce said stock to saidmetering tube and flushing water into said metering tube, an adjustablypositionable plug in said tube providing a constriction for the flow ofstock therethrough, flow sensing means positioned to sense the flow ofstock into said tube, relay means operable by said sensing means tooperate said valve means to terminate introduction of stock and injectflushing water into said metering tube, means operable by said relaymeans to simultaneously move said plug into a position where said plugprovides a lesser constriction to the passage of flushing water than itdoes to stock passage, a first timer means controlling introduction offlushing water to said tube to a predetermined time interval, a counter,means connecting said counter to said relay means, said counter beingarranged to count the number of times said relay means is renderedoperable to introduce flushing water into said tube, a second timercycling the operation of said counter to a predetermined time interval,and a recorder-controller receiving the output of said counter forrecording the number of counts on said counter during each cycle ofoperation of said second timer.

7. The device of claim 6 in which said recorder-controller compares theoutput of said counter with a predetermined value and provides anenergizing signal when said output exceeds said predetermined value.

8. The device of claim 6 which also includes means for rotating saidplug within said metering tube.

9. The device of claim 6 in which said metering tube has a bell shapedoutlet end and said plug is a conically shaped element extending intosaid bell shaped outlet end.

References Cited by the Examiner UNITED STATES PATENTS 2,391,393 4/1960Jones 222-148 X RAPHAEL M. LUPO, Primary Examiner.

1. A CONTINUOUS SHIVE CONTROL DEVICE COMPRISING A METERING MEANS, MEANSFOR SUPPLYING STOCK TO SAID METERING MEANS UNDER A CONSTANT HYDROSTATICHEAD, A CONSTRICTION MEANS IN SAID METERING MEANS PROVIDING AN ORIFICEFOR THE FLOW OF STOCK THERETHROUGH, SENSING MEANS OPERABLE TO DETERMINEA PREDETERMINED DIMINUATION OF FLOW ABOUT SAID CONSTRICTION MEANS, ANDMEANS OPERABLE IN RE-